Most buildings are constructed of a combination of columns (i.e., posts) and beams, which are covered by plywood or some sort of metal or plastic sheeting. In an effort to reduce the overall construction time, however, contractors often construct buildings, and particularly, the exterior walls of buildings, with prefabricated building panels. Constructing a building with such panels increases efficiency because rather than assembling individual components on site, entire wall panels are manufactured on the construction site so that they can be swiftly combined and installed. These prefabricated panels are typically manufactured from steel sheet metal. Thereafter, two panels are placed adjacent to one another and the sides of the panels engage and form a sealed joint.
These interconnected panels may by straight or arched (i.e., curved). Arched panels are typically used to construct an entire metal building. For example, the roof panels are completely arched and extend to the foundation. The design of these buildings is such that the roof panels continue downward and also form the side walls of the building, thereby creating a semi-circular shaped building when viewed from the end.
An arched building constructed of panels has its advantages, but it also has a number of limitations. For example, these panels are typically shaped and sealed together by a single machine, but some of the machines have limited ability to form panels having multiple shapes and sizes. Specifically, the machine's inability to bend and form certain types and gauges of metal may limit the thickness of the panel, which, in turn, limits the panel's strength and rigidity. Thus, a builder is often restricted to the sizes and shapes of buildings that can be constructed of such panels.
Straight panels also have various positive and negative attributes. Regardless of whether the panel is arched or straight, FIG. 1 illustrates a cross section of a known building panel. If the panel is arched, it is bent in a direction about an imaginary axis A—A. The building panel 100 includes a central portion 102 and two inclined side wall portions 110, 112 extending from opposite ends of the central portion 102. The central portion 102 includes a notched portion 108, thereby separating the central portion 102 into two sub-central portions 104, 106.
The building panel 100 also includes two wing portions 114, 116 extending from the inclined side wall portions 110, 112, respectively. A hook portion 120 extends from one wing portion 116, and a receptacle portion 118 extends from the other wing portion 114. As illustrated in FIG. 2, the hook and receptacle portions are designed to interconnect and form a building structure 200 when two building panels 100 are placed adjacent to one another. A further detailed description of this connection mechanism is discussed in U.S. Pat. No. 5,393,173 which is hereby incorporated by reference.
As additional building panels are connected to one another, however, the size of the building structure increases. Therefore, depending upon the orientation of the building structure, the weight of the additional panels may cause the building structure to deflect. Specifically, FIG. 2 illustrates imaginary axis A—A, which intersects the middle of the building panels 100 and the building structure 200. As the building panel bends from axis A—A towards the wing portions 114, 116, the building panel is subject to a positive bending moment. Similarly, as the building panel bends from axis A—A towards the central portion 102, the building panel is subject to a negative bending moment. The size of the bending moment is a function of the amount of force acting upon the building panel and the distance applying such force. Thus, as the force and distance increase, so does the bending moment.
The weight of the building structure is an example of one type of applied force. As the size of the building structure increases, so does its weight. Therefore, as the size of the building structure increases, the building panels are subject to increased bending moments, the direction of which are dependent upon the orientation of the building structure. The inability of the building panels to withstand such bending moments, in turn, imparts design constraints on the building, thereby limiting its size and shape.
The building structure is also subject to other types of horizontal and vertical loads that increase the positive and negative bending moments. As mentioned above, the building panels typically form the exterior walls of a building. Thus, the building panel's are exposed and subject to dynamic climatic changes. For example, snow may accumulate on the roof of a building, thereby imparting a vertical load upon the building panel. Additionally, wind may blow against the side of the building, thereby subjecting the building panel to a horizontal force. These horizontal and vertical forces, caused by the weather, in turn, create additional bending moments. Therefore, these weather conditions impart additional design constraints, thereby further limiting the size and shape of buildings that can be constructed from such panels.
Referring to FIG. 4, there is shown a perspective view of the building panel 100 that is illustrated in FIG. 1. This figure illustrates that the central portion 102 and inclined side wall portions 110, 112 are corrugated. These corrugations 402 are typically formed by passing the panel through a crimping machine. These corrugations (or crimps) generally allow the panels to be formed into a curved shape, the curve having a radius that is a function of crimp depth and spacing. Upon being crimped, the panel's strength and rigidity increases. However, in order to withstand additional bending moments further increased strength and rigidity is required.
The process of forming these corrugations can also present other problems. For example, the crimping machine that forms these corrugations often causes the depth of the corrugations on the inclined side walls of the panel to remain constant while the curve radius of the panel is being changes. Thus, if the curve radius of the panel is tight and the depth of the side wall corrugation is shallow, the inclined side wall buckles due to the excess material not taken up by the corrugation.
The central portion (i.e., belly) of the panel is also typically crimped. Similar to the inclined side wall problem above, if the radius is large or the panel section being formed is straight and the depth of the side corrugation is deep, the central portion of the panel buckles due to the excess material in the central portion not taken up by the crimping process.
Also, the inclined side wall crimping machine and the central portion crimping machine, often referred to as the main crimping apparatus, are physically located apart from one another. Thus, if it is desirable to simultaneously adjust the side wall and main crimping machines, it is not possible to change the depth of the side wall crimping machine. The inability to change the depth of the side wall crimping machine, in turn, causes the buckling effect discussed above. Therefore, there is a need to improve the side wall and main crimping machines in order to minimize the undesirable buckling effects caused by the adjustment of such machines.